One of the approaches to the treatment of psoriasis is via the antiproliferative and prodifferentiative activities of Vitamin D analogs or metabolites. The usefulness of this approach has been partially validated by the recent introduction by Bristol-Myers Squibb of calcipotriene, an effective topical treatment for psoriasis. Penederm Incorporated has recently acquired proprietary rights to 26,26,26,27,27,27-Hexafluoro-1-a,25-dihydroxy Vitamin D3 which is being developed by Sumitomo Pharmaceutical Company, Ltd. as a systemic medication for osteoporosis and has potential for use as a psoriasis treatment. Due to the high potency of the compound, safety evaluation and formulation development require the use of high specific activity radiolabeled material which is not commercially available. Because of metabolic considerations, it is desirable to label the compound in a position other than the alkyl side chain. The labeling scheme, developed by Dr. H. Paaren, utilizes a 9,11 unsaturated C D ring fragment for the tritiation step followed by coupling of an A ring precursor and deprotection to yield the desired product. The proposed scheme provides a facile means for the preparation of a non-labile, high specific activity tritium labeled Vitamin D3 analog for use in safety studies and formulation development. User Details: Experiment Details: State: Fo ster City, CA HPLC Funding Source: Industry NMR Charge: $4115.99 3.5 days Program Income: $3594.90 1 compound